Molecular Dynamics Study of the Structural Properties with Varying B2O3/SiO2 Ratios in the System CaO-SiO2-B2O3

The structural properties for ternary molten CaO-SiO2-B2O3 system with varying B2O3/SiO2 ratios at a fixed CaO content were calculated by molecular dynamics (MD) simulation. The simulation results revealed that with the increasing of B2O3/SiO2 mol ratio, the bond length of B-O was approximately constant at 1.35 angstrom, and the coordination number for B (CNB-O) was observed to vary from 3.40 to 3.51, and the average angle of O-B-O increases from 105 degrees to nearly 120 degrees, implying that the geometric stability of structure is reducing sharply. Also Q(3) and Q(4) tetrahedral species (tetrahedron with three and four bridging oxygens respectively) decrease with the increasing of B2O3/SiO2 mol ratio, and the proportion of (Q(3) + Q(4)) decrease linearly from 0.6 to nearly 0, suggesting that B2O3 may behave as a network-breaking basic oxide in the CaO-SiO2-B2O3 system.